1. Field of the Invention
This invention relates to a packaged semiconductor chip having resistance to ingress of environmental contaminants, capability to make electrical contact to chip terminals remote from the chip periphery and further, to a package which contains an alpha barrier, conserves precious metal, is easily assembled and results in an encapsulated chip with enhanced electrical, mechanical and thermal performance.
2. Description of the Prior Art
Several techniques have been employed to position and affix leads to semiconductor chips prior to encapsulation of the chip in a protective coating.
Current techniques employ a lead frame with a central tab to which the semiconductor chip is attached prior to encapsulation. As described herein at the beginning of the "Description of Preferred Embodiments" section with reference to Prior Art FIGS. 1 and 2, it is known in the prior art to connect terminal pads near the periphery of a semiconductor chip to corresponding fingers of a lead frame.
A common problem with the prior art semiconductor packages has been cracking along the mold parting line where the metal lead frame leads exit. Another problem has been the relatively short path for ingress of environmental contaminants along the metal leads from outside the package to the semiconductor chip. A still further problem has been an inability to reliably form conductors from the fingers of the metal lead frame to chip terminal pads located within the chip surface remote from the periphery of the chip. Moreover, the relatively long wire bond leads required to connect the metal leads to the chip terminals do not permit the crossing of wire bond leads for alternate I/O terminal assignment.